The proportion of Brazilians who define themselves as black or mixed race has risen from 44.7% to 50.7% since 2000. Photograph: Caio Guatelli/LatinContent/Getty

For the first time since records began black and mixed race people form the majority of Brazil's population, the country's latest census has confirmed.

Preliminary results from the 2010 census, released on Wednesday, show that 97 million Brazilians, or 50.7% of the population, now define themselves as black or mixed race, compared with 91 million or 47.7% who label themselves white.

The proportion of Brazilians declaring themselves white was down from 53.7% in 2000, when Brazil's last census was held.

But the proportion of people declaring themselves black or mixed race has risen from 44.7% to 50.7%, making African-Brazilians the official majority for the first time.

"Among the hypotheses to explain this trend, one could highlight the valorisation of identity among Afro-descendants," Brazil's census board, the IBGE, said in its report.

According to the census, 7.6% of Brazilians said they were black, compared with 6.2% in 2000, and 43.1% said they were mixed race, up from 38.5%.

In 1872, when Brazil's first census was conducted, the population was split into just two groups: free people and slaves, who then represented 15% of the population.

The IBGE said that while its researchers had detected the trend about three years ago, the 2010 census was the first full nationwide study to recognise the phenomenon.

In an interview last year Brazil's minister for racial equality, Elio Ferreira de Araujo, attributed the change to growing pride among his country's black and indigenous communities.

Ivonete Carvalho, from the government's racial equality ministry, said African-Brazilians were increasingly willing to stand up and be counted: "I'm here. I'm me. I'm not ashamed of my history."

Race campaigners welcomed the growing number of self-declared African-Brazilians, but the census also underlined how the vast social divide between Brazil's white and non-white populations persists.

The 2010 census – a massive operation which involved about 190,000 census takers visiting 58m homes – found that in major cities white inhabitants were earning about 2.4 times more than their black counterparts.

In Salvador, a former slave port with one of Brazil's largest black populations, the findings were even worse: whites earned 3.2 times more than blacks.

"It is a vicious circle," Marcelo Paixão, an economist from Rio's UFRJ University told O Globo. "Poor salaries lead to worse education, which is a barrier to getting a good job. We need more public policies."

A parallel study, released this week by the Data Popular Institute, provided further evidence of the racial divide that continues to blight Brazilian society. The wealthiest group of Brazilians – known as "Class A" – was made up of 82.3% white people and just 17.7% African-Brazilians.

The same study found that 31.3% of Brazil's white population had private health plans, compared with just 15.2% of the black population.

In an interview this week Ivone Caetano, a prominent African-Brazilian judge in Rio de Janeiro, painted a bleak picture of life in the place some call South America's "rainbow nation".

"In Brazil every black person is going to be a victim of racism, prejudice [and] discrimination, whatever your position," she said. "Our prejudice is disguised and hypocritical."

A news report on the census findings aired by the Brazilian channel Record TV said the rise in Brazil's officially black and mixed race population was "a signal of growing pride among the descendants of Africans". The story was presented by a white reporter and introduced by two white news anchors.